Staying Hydrated in Different Environments

Your body works extremely hard to be at homeostasis or a stable body temperature in all conditions. We perform best when a relatively stable core temperature is maintained. Any drop or rise in core temperature causes a physical reaction in the body to counteract that temperature change. When it’s too cold we shiver which generates energy that warms our body back up. We stop when our core temperature rises to an appropriate level. When it’s hot we rely primarily on evaporation or sweating to return to homeostasis. The harder your body has to work to maintain its proper temperature the less energy is available for athletic performance.




The athlete that can control for environmental factors and focus on their performance will race better. In order to do this you must be fully prepared for training and race conditions. We have put together a few reminders to get you headed in the right direction.




Dress appropriately

Light colors that are breathable are the best for training in the heat. I try to wear a visor with a light top and dark underside to keep the glare out of my eyes. I also make sure my shoes shed water quickly. If the race you are doing is wetsuit-legal, but only 1-2 degrees from the cut off, you might want to consider wearing a sleeveless  wetsuit or speed suit instead. If you overheat in the swim it can make for a long day. If you’re racing in cool conditions layers that are not too baggy are always best so that you can shed as needed, and keep in mind your exercising muscles will be generating body heat so start out feeling a little cool. Dehydration can happen faster in cold conditions if you overdress.



Know your sweat rate

This is always a little tricky because it totally depends on environmental factors and discipline. If you’re training in hot conditions or indoors you need to hydrate nearly twice as much as in other places. Try to mimic your next race conditions as closely as possible to get an idea of your sweat rate. Weigh yourself when finished with hard training sessions.  1lb. of lost weight= 16 oz. of fluid. So if you worked out for 2 hours and lost 2 lbs. your sweat rate is 16 oz. per hour. If you drank any fluids during your workout those need to be added to your calculations. You should NOT have huge fluctuations in weight between the start of each new training session. If you do, you are not properly rehydrating. Rehydration typically requires gradually taking in twice what you lose over a 4-6 hour period, due to sensible and insensible water loss.



How much water loss is too much?

We know that performance decreases when dehydration reaches a certain point, but there is some disagreement on where that happens.  Slight decreases in performance have been observed in as little as 2% body weight loss, and major drops in performance (about 30%) when body weight loss exceeds 5%.  A good guideline is to try to limit total body weight loss to 3%. In hot conditions performance deficits are even greater with the same amount of dehydration, probably because the skin has so much blood flow.  In cool conditions, blood flow can be diverted away from the skin and towards working muscles. So pay particular attention to your hydration and electrolyte balance in hot environments.



Avoiding hyponatremia

Hyponatremia is one of the most common medical complications for long endurance events. Hyponatremia is a low sodium level in the blood and occurs when too much water is ingested without the balance of electrolytes, primarily sodium.  In a marathon for example, runners taking longer than 5 hours are at a much higher risk, especially if they are drinking straight water at aid stations every mile. Often, hyponatremia is present when there is weight gain during a race. So plan your hydration but don’t overdo it with straight water.  Make sure your drink contains adequate sodium, at least 200mg per 12 ounces, or consider salt tablets. Also shift to an electrolyte drink the day or days before competition.




Go into a race and key training sessions properly hydrated and rested

Staying hydrated begins before your race even starts. Drinking 16-25 oz. of sports drink 2-3 hours before your races can be crucially important, but you don’t want to overdo it if you are already properly hydrated (euhydrated). To keep track of my hydration on race day I often fill up a 20 oz. water bottle with First Endurance energy drink. First Endurance EFS drink is made specifically for extreme conditions. EFS has 300 mg of sodium per serving while EFS Pro has 500 mg of sodium which is the highest on the market.  I use EFS for cooler conditions and EFS Pro for warmer conditions. I sip on this until the race starts with the goal of finishing it 20-30 minutes before the race starts. Having that water bottle ensures I get enough fluids and electrolytes, and it also helps ensure I don’t drink too much. The athlete that is properly hydrated and well rested can more effectively maintain a stable core body temperature.



During races and training

During the race I try to drink 1-1.5 bottles of sports drink per hour depending on conditions with a goal of 200-300 calories per hour. The hotter it is the more electrolytes you will need. You are going to have a net loss of hydration during a race, but you want to limit the damage. Most of hydration loss takes place during the run so you want to make sure that you are on top of it during the bike so that you don’t enter the run depleted. Start your hydration and fueling early and evenly drink throughout the bike. Use time or mile markers to help you gauge hydration. 8-10 oz. per 20 minutes is a good place to start. Once you hit the run, carry a water bottle or make sure you don’t skip water stations. On hot training days I run with a water bottle for anything over an hour. In cooler climates I do this only on runs over 1:30.



Plan your fluid intake

In studies, drinking to thirst and planned drinking strategies perform very closely. However, in my experience planning out your drinking is better. Athletes that plan out their drinking rarely end the race with a full water bottle or hydration pack because they forgot to drink. Know your race and come up with a plan. For XTERRA it means researching the course and knowing where you can drink and setting goals for consumption. Practice this plan numerous times before race day so that you can make adjustments if needed and to make sure it works for you. Your plan can have built in adjustments depending on the actual conditions on race morning. If you prepared for 90 degrees and it’s only 70 degrees you should know what changes to make and how your sweat rate will be affected. The more you practice it the more confident you will be on race day.




Hydration pack or water bottles?

In an XTERRA race, a hydration pack can be a good option if you don’t have confidence reaching for a bottle, or if the course is very technical.  Another reason to use a hydration pack is if your bike only holds one bottle and you know there will be more than 45 minutes between aid stations.  One drawback is that it can be hard to tell how much you are drinking and it is common to finish the bike with a hydration pack that is half full. Another negative is the idea of transporting water long distances when it is not necessary.  Know where the aid stations are on the course and plan accordingly. If you opt for a hydration pack, carry only what you need and use a sleek pack that is little more than a bladder, hose, and straps.



Urine color

Check out your urine throughout the day and week during tough training and race blocks. Lighter colors usually mean you are better hydrated. Darker colors mean you are likely dehydrated. Clear urine can mean that you are overhydrated which can deplete your electrolyte levels causing a negative impact on performance.  There are urine charts out there if you’re not sure what color it should be.


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